Feed arrangement for centrifugal separators



Jan. 20, 1959 w. WILSMANN 2,8 ,781

FEED ARRANGEMENT FOR CENTRIFUGAL SEPARATORS Filed June 1, 1956 IZZY-2:23).

United Sttes FEED ARRANGEMENT FOR CENTRIFUGAL SEPARATORS This invention relates to an improved feed arrangement for centrifugal separators. The invention more particularly relates to an improved feed arrangement for centrifugal separators of the sealed or closed type' in which the outlets for the separated components are sealed from each other, from the feed of material to be centrifuged and preferably from the ambient atmosphere in a fluid-tight manner.

In centrifugal separators the passages for the transportation of the material to and from the bowl generally extend through the rotating central spindle of the bowl. In closed or sealed separators the outlets for the separated components are sealed from each other and from the feed of material to be centrifuged by means of stationary packing seals or sleeves which surround the rotating central spindle in fluid-tight frictional sealing engagement therewith. Due to the high speed of rotation of the bowl, the friction between the seal, which is generally constructed of rubber, and the spindle is relatively high. The flow of liquid through the pipe or conduit formed by the spindle, however, prevents an overheating and injury of the seal. An interruption of the feed for a period of time, for example, of only a few seconds may, however, on the other hand allow a considerable rise in temperature causing injury to or completely destroying the seals. In order to avoid such damage, upon commencement of the centrifuging operation, the sealed separators may be placed in operation only after the feed has been opened, preferably after liquid has been allowed to how through the discharge lines.

In some centrifuges the material to be centrifuged is fed from the bottom through the drive spindle of the centrifuge which is constructed hollow for this purpose, and which is provided with a centrifugal pump at the lower end of the spindle. The packing seals used in these centrifuges are positioned in the upper part of the pump inlet housing. In centrifuges of this type, a reduction of the liquid feed can cause damage to the seal on the inlet side of the pump in a very short time since the same will no longer be sufficiently wetted or cooled by the liquid feed. When such damage occurs, it is necessary to interrupt the centrifuging operation and to replace the damaged seal, which causes a considerable loss of time in addition to the cost of replacing the seal.

One object of this invention is a feed arrangement for a centrifugal separator of the sealed type which assures cooling and lubrication of the packing seal in the case of variations or even interruptions of the feed. This and still further objects will become apparent from the following desscription, read in conjunction with the drawing.

The invention is applicable to centrifugal separators having a rotating central spindle or pipe, which will be referred to as a spindle herein, forming the liquid inlet conduit leading to the bowl interior. In accordance with the invention, a stationary substantially liquid-tight housing is provided surrounding the upper portion of atent ice the spindle with the interior of the housingin liquid communication with the inlet conduit defined by the spindle. Liquid inlet means are provided for the passage of liquid into the interior of the housing and a stationary packing seal is connected to the lower portion of the housing through which the spindle extends in sealing engagement with the spindle. A liquid trough is defined in the lower portion of the housing adjacent to the packing seal and pump means are positioned above the trough for pumping liquid through the housing from the liquid inlet through the housing to the liquid inlet conduit. A stationary weir is connected to the housing above the housing inlet and extends between the pump and the trough. Fig. 1 shows a vertical cross-section of an embodiment of a feed arrangement in accordance with the invention.

Referring to the embodiment shown in the drawing, 9 represents the spindle or central pipe of a centrifugal bowl of a centrifugal separator. The spindle is positioned coaxially with the axis of rotation of the bowl and rotates with the bowl. The spindle is: hollow and open ended on top with the hollow interior defining a liquid inlet conduit 8 for the material to be treated leading to the bowl interior. A liquid outlet conduit 10 is also defined through the spindle for discharging the centrifugally treated liquid from the bowl. A closed housing 11, which is preferably fluid-tight, surrounds the upper end of this spindle 9 with its interior in flow communication with conduit 8. At the bottom portion of the housing where the spindle extends through the housing wall a stationary packing seal in the form of a rubber packing sleeve 5 is provided. The packing sleeve is clamped between the housing wall and the member 12 and presses in liquid sealing frictional engagement with the spindle. The lower portion of the: housing defines a liquid trough 4 over the packing sleeve 5. An inlet pipe 1 is connected to the housing above the trough 4. An annular weir 3 extends from the peripherial wall of the housing above the inlet pipe 1 toward the central portion of the housing. The weir 3 and the opposed wall of the housing define an annular liquid passage leading from the inlet pipe 1 to the trough 4. Connected on the lower side of the weir 3 are flow-impeding wings 2. A pump impeller 6 is positioned above the weir 3 and connected to the upper end of the spindle for rotation therewith. A guide plate 7 is positioned above the pump impeller 6 for directing liquid pumped by the impeller through the housing into the interior of the inlet conduit 8.

The upper end of the housing is sealed by a removable cover plate 13 held in place by the set screw 14.

The bottom portion below the closed housing 11 is an outletv housing 15 which has a packing seal 18 at its lower end in sealing frictional contact with. the spindle 9. The housing 15 also defines a liquid trough 16 above the seal and has an outlet pipe 17 positioned at its upper portion above the trough. The outlet conduit 10 leads into this housing and is connected at its lower end to a conventional discharge device in the bowl. In connection with centrifuges in which the material treated is separated into two or more components, a separate housing 15 may be provided for each separated components. When more than one housing 15 is provided, the subsequent housing 15 may be constructed in identical man ner as the housing shown and positioned directly below the housing shown.

In operation, the liquid to be centrifuged is fed to the separator into the housing 11 through the inlet pipe 1 which may be connected with a closed line or an open inlet vessel in the conventional manner. The liquid flows below the weir 3 and fills up the trough 4 above the packing sleeve 5. As the centrifugal bowl and the spindle 9 rotate, the pump impeller 6 is also caused to rotate. The impeller 6, however, cannot act upon the liquid in the trough until its level is above that of the weir 3. At this point, the pump 6 conveys liquid in an upward direction'so that the same passes against the guide plate 7 and is directed into the inlet conduit 8 passing into the interior'of the bowl in the conventional manner. If the supply of liquid through the inlet pipe 1 is interrupted or diminished, the pump impeller 6 will fully continue to convey the liquid until its level falls below the weir 3. At this point the liquid will remain in the trough 4 as the pump can no longer act upon the same and since the same is substantially stationary due to the wings 2 positioned on the lower side of the weir 3. Therefore, even with an interruption or diminishing of the flow, the packing sleeve will be cooled and lubricated by the liquid in the trough.

Due to the special shape of the weir 3, which is bent downwardly near the inner lower edge of the feed pipe,

and due to the disc-shape development of the 'centrifugal pump, a minimum space is required in the axial direction. As a result of this, the rotating parts are closer to bowl, which is very advantageous for satisfactory operation of the bowl.

After the liquid has been treated as, for example, separated in the bowl, the same is discharged through the discharge conduit 10 by means of the centrifugal pressure or a suitable discharging device. Discharged liquid flows into the interior of the housing filling the trough 16, and finally overflowing through the outlet pipe 17. The liquid in the trough 16 will cool and lubricate packing seal 18, and a quantity of this cooling and lubricating liquid will remain in the trough 16 even upon interruption or diminishing of the flow through the centrifuge.

The feed arrangement, in accordance with the invention prevents damage to the packing seals upon decrease of the feed material to be centrifuged and thus prevent time consuming interruption of operation. In addition to this, the arrangement assures a quite operation of the bowl.

While the invention has been described in detail with reference to the specific embodiment shown, various changes and modifications will become apparent to the skilled artisan which fall within the spirit of the invention and scope of the appended claims.

I claim:

1. In a centrifugal separator having a rotating central spindle defining a liquid inlet conduit, the improvement which comprises a stationary substantially liquid tight housing surrounding the upper portion of said spindle with the housing interior in liquid communicationwith said inlet conduit, liquid means for the passage of a liquid into the interior of said housing, a stationary packing seal connected to the lower portion of said housing in sealing engagement with said spindle, a liquid trough defined in the lower portion of said housing above said packing seal, pump means positioned above said trough for pumping liquid through said housing from said liquid inlet means to said liquid inlet conduit, and means defining a stationary weir connected to said housing and extending between said pump means and said trough.

2. Improvement according to claim 1 including flow impeding wings connected to the lower side of said weir.

3. Improvement according to claim 1 in which said liquid inlet means comprises a liquid inlet pipe and in which Said weir defines with the opposed housing wall an annular passage leading from said inlet pipe to said trough.

4. Improvement according to claim 3 in which said weir is an annular weir extending from in sealing engagement with the peripheral portion of the housing wall above said inlet pipe toward the central portion of the housing interior.

5. Improvement according to claim 4 including flow impeding wings connected to the lower portion of said weir.

6. Improvement according to claim 5 in which said pump means comprises a pump impeller connected for rotation with the upper end portion of said spindle.

7. Improvement according to claim 6 in which said spindle is a hollow spindle having an open upper end and defining said liquid inlet conduit through the interior thereof.

8. Improvement according to claim 7 in which said packing seal is a rubber packing sleeve.

9. Improvement according to claim 8 in which said inlet pipe is positioned above said trough.

10. Improvement according to claim 1 in which said pump means comprises a pump impeller connected for rotation with the upper portion of said spindle.

References Cited in the file of this patent UNITED STATES PATENTS 2,651,455 Strezynski Sept. 8, 1953 FOREIGN PATENTS 739,481 Germany Sept. 23, 1943 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,869,781 January 20, 1959 Wilhelm Wilsmann It is herebj certified that error appears in the-printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 38, for "peripherial" read peripheral column 4, line 4, for "liquid means" read liquid inlet means o Signed and sealed this 5th day of April 1959 SEAL) Attest:

KARL H. AXLINE Attesting Officer ROBERT c. WATSON Commissioner of Patents 

